paper

Wide companions to Hipparcos stars within 67 pc of the Sun

arXiv:1208.0626 · doi:10.1088/0004-6256/144/4/102

Abstract

A catalog of common-proper-motion (CPM) companions to stars within 67 pc of the Sun is constructed based on the SUPERBLINK proper-motion survey. It contains 1392 CPM pairs with angular separations 30" < ρ< 1800", relative proper motion between the two components less than 25 mas/yr, magnitudes and colors of the secondaries consistent with those of dwarfs in the (M_V,V-J) diagram. In addition, we list 21 candidate white-dwarf CPM companions with separations under 300", about half of which should be physical. We estimate a 0.31 fraction of pairs with red-dwarf companions to be physical systems (about 425 objects), while the rest (mostly wide pairs) are chance alignments. For each candidate companion, the probability of a physical association is evaluated. The distribution of projected separations s of the physical pairs between 2 kAU and 64 kAU follows f(s) ~ s^{-1.5}, which decreases faster than Öpik's law. We find that Solar-mass dwarfs have no less than 4.4% +/- 0.3% companions with separations larger than 2 kAU, or 3.8% +/- 0.3% per decade of orbital separation in the 2 to 16 kAU range. The distribution of mass ratio of those wide companions is approximately uniform in the 0.1<q<1.0 range, although we observe a dip at q=0.5 which, if confirmed, could be evidence of bimodal distribution of companion masses. New physical CPM companions to two exoplanet host stars are discovered.

To appear in the Astronomical Journal. Electronic data table available on request from the authors

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